From a 1/4 Tag.
As one movement, Extend twice & new Outsides Trade 
  (or Left-shoulder Trade if the starting formation was a L-H 1/4 Tag).
Ends in a 1/4 Tag.
Notes:
- 
The handedness of the setup does not change:  
- A R-H 1/4 Tag ends in a R-H 1/4 Tag;  
 - A L-H 1/4 Tag ends in a L-H 1/4 Tag.  
 
 - 
From a R-H 1/4 Tag, all shoulder passes are Right-shoulders.  
    From a L-H 1/4 Tag, all shoulder passes are Left-shoulders.
 - 
Ping Pong Circulate should be envisioned as two separate Circulate paths.  There is an
    inside path and an outside path.  Sometimes, a caller
    may activate only one of the Circulate paths (e.g., Ping Pong Circulate, Girls go twice; or,
    Boys only Ping Pong Circulate).
 
| 
 Inside path:   
 
 |   | 
 
 |  before Ping Pong Circulate |   | after
  |   
 | 
 Outside path:   
 
 |   | 
 
 |  before Ping Pong Circulate |   | after
  |   
 | 
| 
 Boys only Ping Pong Circulate:   
 
 |   | 
 
 |  before Boys only Ping Pong Circulate(    = Boy)  |   | after
  |   
 | 
Once I heard a caller call Ping Pong Circulate 1 & 1/2.
  He wanted a Ping Pong Circulate followed by an Extend.
  In my opinion, this is a cute gimmick, but technically incorrect. 
Single Ping Pong Circulate [C4]:
 From a Single 1/4 Tag.  
  As one movement, Extend twice and the new Ends U-Turn Back.  
  Ends in a Single 1/4 Tag.  
  The direction toward which to do the U-Turn Back is undefined, hence it is inappropriate
  to follow this movement with a Roll.
| 
 Single Ping Pong Circulate:   
 
 |   | 
 
 |  before Single Ping Pong Circulate |   | after
  |   
 |